ST launches more Cortex-M3 parts, previews M0, M4 based devices

Alexander Czajor, ST's microcontroller marketing manager for EMEA, said: "By running the core at 120MHz, designers will be able to use the full performance of the Cortex-M3 core. However, at 120MHz, the core is at the limit of its performance." According to Czajor, the mcus consume 188µA/MHz because the 90nm flash process allows the core to run at 1.2V. The mcus can run at 120MHz through the inclusion of the advanced real time memory accelerator (ART). "If you have a slow flash interface," said Czajor, "you have to add wait states; you can't fetch data at the speed it's needed. However, with ART, there is a 128bit wide interface, which allows up to eight instructions to be loaded at a time." The ART features 64 128bit registers for code and a further eight 128bit registers for data. "If your code has branches," Czajor continued, "once it has been fetched from flash, it will in most cases remain in this matrix and the instructions will be available with zero wait states." It is this feature that allows the core to run at 120MHz. "We could push the core's performance without ART," Czajor noted, "but it would be at a cost. A system would need a bigger flash memory, which would draw more current and produce more emi. The most economic solution is to make the flash memory smaller." Four variants will be available in the middle of 2011. The F205 range features from 128k to 1Mbyte of flash, with up to 128k of sram and a full speed USB On The Go interface. The F207 range adds a further USB OTG port, as well as a 10/100 Ethernet MAC. Meanwhile, the F215/217 versions add a cryptographic processor. A range of packages can be specified.